1. Field of the invention
The present invention relates to a chucking device used for the manufacture of, for example, electrophotographic photoconductor drums having a photoconductive layer on the outer circumferential thereof. The chucking device is used to hold a drum to keep it substantially vertical when the drum is immersed in a coating liquid containing a photoconductive substance and a volatile solvent.
2. Description of the prior art
When a conductive drum such as an aluminum drum is to be coated with a coating liquid containing a photoconductive substance for the production of an electrophotographic photoconductor, the coating liquid must be applied uniformly on the outer circumferential surface of the drum. One known process for applying a coating liquid uniformly on the outer surface of a drum is an immersion process in which the drum is first immersed in the coating liquid and then extracted therefrom in the axial direction at a prescribed speed.
In such an immersion process, the drum is kept substantially vertical when immersed into and extracted from the coating liquid. To apply the coating liquid uniformly over the entire outer circumferential surface of the drum, the drum must be held in such a manner that a chucking device and other attachments do not contact the outer circumferential surface of the drum.
Japanese Laid-Open Utility Model Publication No 1-81656 discloses a chucking device which holds a drum and keeps it substantially vertical by supporting the inner circumferential surface thereof. This chucking device includes a balloon which is inflated to tightly contact the inner circumferential surface of the drum for the purpose of holding the drum in a substantially vertical manner.
The drum is thus held by the above-mentioned chucking device while being uniformly coated with a coating liquid on the outer circumferential surface thereof. Since the balloon tightly contacts the inner circumferential surface of the drum, there is hardly any possibility of the coating liquid entering the interior of the drum from the lower opening thereof when the drum supported vertically is immersed in the coating liquid.
In the manufacture of an electrophotographic photoconductor drum, as described above, the coating liquid must be uniformly applied onto the surface of the drum to ensure the formation of a photoconductive layer of a predetermined thickness. In the aforementioned immersion process, however, the coating liquid cannot be uniformly applied to the drum if the drum is not vertically held. With the above-mentioned chucking device, it is difficult to keep the drum vertical. The drum tends to come off its vertical position when the balloon is inflated.
Furthermore, in such a chucking device, the balloon is inflated by being filled with air to hold the drum. Therefore, if the balloon holding the drum ruptures, or if the air leaks from the balloon, this will cause the drum to fall off from the chucking device. This may damage the drum and may even be dangerous.